Articulated marine platform

ABSTRACT

The invention relates to a monopad articulated marine structure for offshore waters, which unit comprises an anchoring base, a work platform which is normally positioned above the water&#39;&#39;s surface, and an intermediate support column. The latter is operably connected at opposed ends to the respective base and deck or platform whereby the entire unit can be readily floated to and from working sites.

United States Patent [1 1 Pogonowski et al.

[ 1 Jan. 9, 1973 [54] ARTICULATED MARINE PLATFORM [75] Inventors: Ivo C.Pog'onowski; Paul D. Carmichael, both of Houston, Tex.

[73] Assignee: Texaco, lnc New York, NY.

[22] Filed: Dec. 7, 1970 [21] Appl. No.: 95,663

[52] U.S. Cl. 61/465, 9/8 P, 114/5 D [51] Int. Cl. ....E02b 17/00, E02d27/04, B63b 35/44 [58] Field of Search ..6l/46.5; 114/.5 D; 9/8 P [56]References Cited UNITED STATES PATENTS 8/1970 Vilain ..61/46.5 8/1970Miller 3,246,475 4/1966 Booth et al ..61/46.5 3,007,317 11/1961 Suderow..6l/46.5 3,273,526 9/1966 Glosten 61/46.S X 3,563,043 2/1971 Nelson..61/46.5

FOREIGN PATENTS OR APPLICATIONS 1,484,526 3/1969 Germany ..61/46.5

OTHER PUBLICATIONS Ocean Industry, pub of Mar. 1967, pp. 56, 57, 58114-115 Primary Examiner-Jacob Shapiro Attorney-Thomas H. Whaley andCarl G. Reis [57] ABSTRACT The invention relates to a monopadarticulated marine structure for offshore waters, which unit comprisesan anchoring base, a work platform which is normally positioned abovethe waters surface, and an intermediate support column. The latter isoperably connected at opposed ends to the respective base and deck orplatform whereby the entire unit can be readily floated to and fromworking sites.

1 Claim, 5 Drawing Figures ARTICULATED MARINE PLATFORM BACKGROUND OF THEINVENTION In the exploration for and production of offshore petroleumsources, use of more. versatile marine platforms has been the object ofmuch consideration and innovative engineering. To permit such platformsto function in the deeper waters to which such exploration anddevelopment activities are gravitating, the platform must be adapted tosatisfactorily withstand excessive stresses and strains due to theenvironment.

One form of such a platform which embodies many of the virtues of astationary, as well as floating type unit, comprises a buoyant columnthat is free to move within limitations while being firmly anchored tothe ocean floor. The column normally supports a work deck at the upperend, which deck is disposed beyond the oceans surface.

One disadvantage of such units for deep water use is the difficulty intransporting or moving the platform between a shore based constructionsite and a distant offshore operating site, or between working sites.Preferably, the entire unit is controllably buoyant, which featurepermits its being floated into place as well as being relocated at analternate drilling location.

Toward achieving an improved platform of the type contemplated, thepresently disclosed articulated unit embodies essentially threesections. Each of the sections is at least partially buoyant to permitbeing floated into place and yet facilitate the proper positioning ofthe platform for drilling and producing purposes.

The platform includes a work deck which is constructed as to beself-buoyant. The deck accommodates the normal complement of equipmentpeculiar to such offshore drilling and producing structures. The deck isnormally supported in placein a substantially horizontal disposition tomaintain said equipment above the waters surface. The lower end of themarine structure is provided with a controllably buoyant anchoring basewhich embodies anchoring means suchas piles or other facility forrigidly maintaining the base in place at a particular working site.

The deck andbase respectively are pivotally connected by a rigid,telescoping, column-like structure which operably engages each of saidunits. When in the working position, the column is buoyed into asubstantially upright disposition; when being transported between sitesit is horizontal.

DESCRIPTION or THE DRAWINGS" FIG. 1 is an elevation view showing themarine platform in a horizontally, floating position.

FIG. 2 is a top viewofFlG. 1.

FIG. 3 is a sectional view of the marine platform on an enlarged scale.7

FIG. 4 is a segmentary view in partial cross section showing the decksection.

FIG. 5 is an elevation view showing the platform in a vertical, floatingposition.

A preferred embodiment of the disclosed marine platform 10 as shown inthe figures, includes a work deck unit 11 which comprises in effect abarge-like vessel incorporating internal, controlled buoyancy tanks notpresently shown. When in operating position, the upper surface of deck11 carries the normal complement of drilling equipment such as a derrickl2, draw works 13, rotary table 14, as well as crews quarters, storagefacilities and the like.

Anchoring member 15 of platform 10 comprises a pad-like foundation base16 which as shown, is held at the ocean floor forming a generally planerfoundation. Base 16 also embodies internal, controllably buoyant tanks,operable from the waters surface to permit said anchoring member to becontrollably submerged to the ocean floor, or raised from the latter asrequired.

An elongated column-like structure 17 is disposed generally uprightly inthe water, being operably connected at its upper end to the deck 11, andat its lower end to anchoring member 15 When column 17 is so disposed,deck 11 is supported as to be rigidly fixed to the column by a bracingmeans such as removable brace arms 18 extending therebetween. However,the latter are positioned subsequent to column 17 being raised to itsvertical disposition from its horizontal at titude at a drilling site.

Deck section 11 is formed of upper and lower spaced apart deck plates 22and 23 connected peripherally by an intermediate wall whereby to formthe unit into a substantially water tight hull. The deck-interspace 24is as mentioned, provided with the equipment and facilities peculiar toan offshore platform of the type contemplated. Referring to FIG. 2, deckunit 11 is provided on one side with a slotted portion defined byparallel walls 26 and 27 that extend from the deck center, outwardly toone side. Said slotted portion is of sufficient width to accommodate theupper end of column 17 when the latter is raised to a horizontaldisposition.

Referring to FIGS. 3 and- 4, deck interspace 24 is further provided witha bearing means including spaced apart journals 31 and 32 having alignedcenter openings which accommodate a shaft 33 extending therethrough.Shaft 33 is adapted to slidably engage in turn the upper end 36 ofcolumn 17 whereby to permit relative movement between the shaft andcolumn respectively during the transition period as the columnadjusts'from horizontal to vertical disposition.

Anchor member 15 disposed at the opposed'or lower end of column 17 isformed with a plurality of compartments or tanks 38 and 39. Said tanksare adapted to be remotely and controllably flooded to regulate both thedisposition and the attitude of the anchor member either in the water orat the ocean floor. As shown in FIG. 3, said anchor member includesupper and lower, spaced apart panels 41 and 42'w'hich, together with asurrounding wall, form the controllably buoyant compartments '38 and 39.

Anchor member 15, as in the instance of the above mentioned deck 11, isprovided with a similar slotted section 46 extending from a pointsubstantially centrally of the anchor, outwardly to the edge. Thus, saidslot 46 is sufficiently wide to register the lower end 48 of column 17as the latter is buoyed toa horizontal disposition.

Anchor member 15 is further provided with clamping means 51 for engagingthe lower positioned pivotal ball 21 on column 17. As shown in FIGS. 3and 4, said clamping mechanism includes a plurality of radiallypositioned jaws 53, 54 and 56, each having an inner face that slidablyengages a substantial portion of the pivotal ball 21 surface. Saidslidingengagement permits restrained oscillatory movement of column 17about hinged joint 19 while maintaining the columnat the desiredlocation. The ball clamping mechanism 51 can be sufficiently versatilewhereby the respective jaws 53, 54 and 56 are adjustable to engage ball21. However, a similar retaining grip can be achieved with a relativelystationary set of jaws having sufficient lateral space, betweenadjacently positioned jaws to permit the column lower end 48 to registertherebetween when the column is in the longitudinal position.

Column 17 comprises as'mentioned, upper and lower sections 36 and 48respectively, which are preferably axially aligned to permit telescopingmovement therebetween. Column 17 upper end 36 includes a body section 58which can be formed of an elongated cylindrical member, or can beformedof a lattice work of structural beams. The column upper end 36 furtherincludes a constricted neck 59 which comprises the base for an elongatedbearing head 61. The latter is provided with a transverse openingextending therethrough in a direction normal to the column longitudinalaxis. As shown in H6. 3, when properly assembled, the column bearinghead 61 slidably registers shaft 33, which in turn is received in therespective journal bearings 31 and 32 supported within deck 11. As soarranged, the column 17 is free to move restrictively within an arc ofapproximately 90 whereby the column can assume a parallel relationshipto the waters surface, while remaining in operable engagement with deck11. 1

The column 17 lower end 48includes base portion 63 having anelongatedcavity 64 extending longitudinally thereof and adapted to receive theupper column body section 58. Said longitudinal cavity 64 extendssubstantially the length of the column end 48, terminating abovebuoyancy tank 66. Cavity 64 is of sufficient length to'permit the upperbody section 58 to be slidably pos'itioned therein for substantially theentire length of the latter whereby to minimize the length of the columnduring periods when it is being floated between operating sites. J

The respective column end segments 36 and 48 are maintained inlongitudinal alignment by'a guide meanswhich prohibits relativerotational movement between said'two members. Each of said columnsegment members is further. provided with a series of longitudinallyspaced apart lug openings 68. Said openings are alignable withcorresponding openings in the mating lower column segment to receive oneor more positioning pins 71 carried in lug ring 72 disposed at the upperend of lower column section. Said pins 71 are remotely actuatable tolock or release the columnsegments as required.

Column 17 lower end as previously noted is provided at its lower endwith a pivotal ball 21 which slidably engages the socket formed withinthe clamping mechanism 51 of anchor member 15. Said ball 21 is connectedto the column lower end at a constricted collar 73 which terminates inan elongated shank 74. The latter as mentioned is of sufflcient width tofit intermediate adjacently positioned jaws 53 and 56 when the latterare in the sliding engagement with said ball 21. As shown in FIG. 3,column 17 is maintained within the anchoring member 15 as a safetyfeature by one or more cables 76 extending from the ball lower end tothe adjacent walls of the anchor cavity 77.

operationally, the articulated structure is normally transported orfloated between drilling sites while in Y Therefore, in spite of roughseas and other adverse conditions, there will be a minimum of strainimposed on the telescoped column during floating movement when thecolumn is in a horizontal position.

To facilitate said movement between operating sites, the column segmentsare normally disposed in a fully contracted position whereby therespective portions are received one within the other. At the drillingsite, to properly position the column. in an upright alignment,thebuoyant tank or compartments 38 and 39 within the anchor 15 arecontrollably flooded. As flooding continues, the buoyancy of the anchorunit 15 will be effected to the point where the latterwill'submerge,thereby aligning the column into an upright disposition.

By controlled buoyancy of both the column tanks 66 and 79 as well as theanchor unit 15, the entire structure will be floatably supported by thedeck'member 11. Release of the intercolumn locking means at ring 72 willthen permit the lower end of the column to slidably detach from thecolumn upper end, after which anchor 15 will descent to the ocean floorand engage the latter.

In the desired operating position, and as shown in FIG. 5, deck 11 ispreferably raised beyond the waters surface to maintain the deck as wellas the equipment carried thereon out of contact with the water. Thus,the column 17 upper end 36 will be extended either by mechanical andhydraulic means or it can be floated to bring the deck beyond the waterssurface by controlled regulation of upper buoyancy tank 79 within thecolumn end. 3 l l In either instance, and as shown in FIG. 3, with thedeck raised to the upper position, or immediately prior to thisadjustment, braces 18 are fastened into position firmly connecting deck11 with the column upper end whereby to rigidize. the relationshiptherebetween. Thus, sufficient weight will be exerted on the anchor tomaintain the latter at its desired spot while still permittingoscillatory movement of the column as well as thedeck in response towind and wave movement. However, the anchor 15 can be provided withancillary positioning means such as a plurality of piles 81 or anchorsdisposed thereabout which can, be driven into the substratum to assure a.firm positioning of the anchor in spite of lateral displacing'forces'.

With the platform in place, in the instance of a drilling operation, thenecessary derrick 12 and draw works 13 will be hoisted into place at thedesired location on the deck. The drilling operation can then be carriedout through the deck and downward-whereby to form one or more well boresinto the ocean floor either through the anchor 15 or adjacent thereto.

When it becomes necessary to discontinue an operation at a particularsite, the entire tructure is released from its fixed location bydisconne ting from the wells drilled, and by separating from therespective anchoring piles 81 in the normal manner. By controlledcontraction, column 17 is telescopically brought together to permit thedeck to be buoyantly supported at the waters surface. Thereafter,controlled blowing of the ballast tanks or compartments 38 and 39 in theanchor, will adjust the buoyancy of the latter until it is freed fromthe ocean floor and will gradually ascend to the waters surface.

Other modifications and variations of the invention, as hereinafter setforth, may be made without departing from the spirit and scope thereof,and therefore, only such limitations should be imposed as are indicatedin the appended claims.

We claim:

1. An articulated, controllably submergible marine platform adapted tobe floatably transported to, and at least partially submerged atanoffshore site, said platform including;

an elongated column having opposed upper and lower ends,

an anchor pivotally connected to said column lower end. to permitrelative movement between said anchor and said column, a buoyant deckoperably engaging said column upper end and including;

means for controllably regulating the deck buoyancy to at leastpartially support said platform within a body of water as well as at thewaters surface, a unitary bearing means carried on said deck,

a slotted portion formed in said deck and extending between said bearingand the deck outer edge, said slotted portion being'of sufficient widthto register said column upper end therein when said column is adjustedto a horizontal position in'the waters surface,

said column upper end engaging said unitary bearing means whereby topermit pivotal movement therebetween when said deck is in horizontaldisposition in the waters surface, and to permit the subsequent pivotingof the column to an upright disposition, to be floatably supported bysaid buoyant deck at said offshore site.

1. An articulated, controllably submergible marine platform adapted tobe floatably transported to, and at least partially submerged at anoffshore site, said platform including; an elongated column havingopposed upper and lower ends, an anchor pivotally connected to saidcolumn lower end to permit relative movement between said anchor andsaid column, a buoyant deck operably engaging said column upper end andincluding; means for controllably regulating the deck buoyancy to atleast partially support said platform within a body of water as well asat the water''s surface, a unitary bearing means carried on said deck, aslotted portion formed in said deck and extending between said bearingand tHe deck outer edge, said slotted portion being of sufficient widthto register said column upper end therein when said column is adjustedto a horizontal position in the water''s surface, said column upper endengaging said unitary bearing means whereby to permit pivotal movementtherebetween when said deck is in horizontal disposition in the water''ssurface, and to permit the subsequent pivoting of the column to anupright disposition, to be floatably supported by said buoyant deck atsaid offshore site.